1. Field of the Invention
This invention relates to a method for producing wire and more particularly to a method for producing wire for reinforcing rubber articles from cold rolled steel coils.
2. Description of the Prior Art
Steel wire is conventionally manufactured by preparing a melt of a specific composition, casting the melt, thermomechanically working the cast product, and wire drawing. Frequent intermediate annealing is required to restore ductility in order to achieve substantial reductions in cross-sectional area. To produce fine diameter, high carbon wire of approximately 20 mils and smaller coupled with specific mechanical properties or microstructure is quite expensive. The wire is expensive because of a low product yield and the numerous processing steps required to ultimately arrive at the final diameter and specific mechanical properties or microstructure.
As used herein the term "wire" is defined as a product with a filamentary or ribbon-like shape characterized by a small cross-sectional area. Furthermore, the actual cross-section can be round or flat.
The terms round wire, flat wire, ribbon or filament may be interchanged in this specification. However, the product referred to is always one with a small cross-sectional area.
In U.S. Pat. No. 2,074,713 a method is disclosed for making wire from sheet metal. Sheet metal is rolled through a grooving mechanism so as to provide channels on opposite sides of a sheet which define the wires to be produced. The channels are subsequently separated by passing the sheet through a shearing apparatus thereby providing a plurality of wire-like elements of polygonal cross-section. The disclosed process is suitable for producing stock for welding rods. Such rods are generally much larger in diameter than 20 mils.
Another method for producing wire is to roll round rod into flat wire in those instances where slitting as a method of production is either very difficult or impossible. It is known in the prior art that this technique is applicable for producing wire with aspect ratios of more than 100.
In volume 3 of the Steel Wire Handbook, 1972 edition, at page one there is the implication that obtaining wire with a small cross-sectional area is not practical or possible by slitting. Furthermore, the prior art is devoid of a method for producing such small cross-sectional wire by slitting so that the slit product has an aspect ratio of less than about 25 and for realizing an extended knife life during slitting.
The method of the present invention produces wire with a small cross-sectional area and good mechanical properties by slitting steel strip wherein the slitting is characterized by extended knife life.